Heating or flame hardening apparatus



May 4, 1948. H. B. GILSON 72,440,716

HEATING OR FLAME HARDENING APPARATUS v Filed Sept. 27, 1940 INVENTORHIRAM B. GILSON ATTORNEY Patented May 4, 1Q48 HEATING OR FLAME APPARATUS1 a Gilson, West Allis, we, assignor a The Linda Air Products Company, acorporation of Ohio Application September 27, 1940. Serial no. 358,604

(c1. ass-5) g 5 Claims.

, 1 I This invention relates to apparatus for heating surfaces of metalarticles by high temperature heating flames, and more particularly toapparatus for flame hardening articles such as gear teeth, the ends ofwhich tend to become overheated.

In flame hardening articles, such as gear teeth,

in the usual manner, one or more high temperature heating flames aredirected against successive portions of either or both wearing surfacesof the gear tooth, to heat such successive surface portions to atemperature at or above the critical range. The heating flames arefollowed by quenching Jets which cool the heated sur- "face portions ata sufficiently rapid rate to harden the same. For simplicity ofapparatus and operation, it is desirable to effect a substantiallyconstant relative speed of traverse of the heating flames across thesurfaces. However, with a relatively constant speed of traverse, thereis a tendency for the ends of the gear tooth to become overheated, sincethere is less metal at the ends I to conduct heat away. When the end ofthe wearing surface of a gear tooth is overheated, there may be adisparity in hardness between the end and the remainder of the toothsurface, and also a tendency for the end of the tooth to chip, spall, orcrack. Thus, it is desirable to heat the end of a wearing surface of agear tooth, or similar portions of other metal articles, tosubstantially the same temperature as the remainder of the surface.

Heretofore, an increase in the rate of relative speed of traverse hasbeen utilized to cause less heat to be applied to surface portions whichtend to become overheated, but in order to achieve the necessaryaccuracy in speed control, a complicated set-up or expensive governingapparatus must be used. Consequently, an object of this invention is toprovide apparatus for heating or flame hardening in which the amount ofheat applied to a surface portion which tends to become overheated isreduced, but in'which a relatively constant rate of traverse may bemaintained.

Among other objects of this invention are: to provide apparatus forheating or flame hardening a surface ,of a metal article, by which thetendency for any portions of such surfaces to become overheated isavoided: to provide such apparatus which is easily controlled andeffective in operation; and to provide such apparatus which comprises-arelatively inexpensive addition to existing apparatus for heating orflame hardening surfaces of metal articles, particularly gear teeth andthe like.

Further objects and novel features of this invention will becomeapparent from the, following description and accompanying drawing, in

2 for flame hardening the wearing surfaces of gear teeth, but equippedwith parts added thereto in accordance with this invention: and

Fig. 2 is an enlarged partial end elevation of the apparatus of Fig. 1,partially in section taken along line 2-,-2 of Fig. 1.

In the apparatus of this invention, high temperature heating flamesproduced by a combustible mixture of oxidizing gas, such as oxygen, andafuel gas, such as acetylene, are preferably utilized; and thetemperature andintensity of the heating flame or flames is lowered asany surface portion, which would otherwise tend to become overheated, istraversed. In accordance with this invention, the intensity of theheating flame or flames is lowered by reducing the amount or pressure ofoxidizing gas or oxygen which, with the fuel gas, forms the combustiblemixture producing the heating flames.

The invention may be carried out by the apparatus illustrated in thedrawing, which includes a pair of blowpipes B and 3' provided with headsH and Hi, each of which is adapted to direct heating flames followed byquenching jets against one of the opposite sides or wearing surfaces ofa tooth T of a spur gear (5. The blowpipes 'B and B are mounted, by asupport 8, on a carriage C which runs along a track K and in a directionparallel to the sides-of tooth T. Blowpipes B and B are supplied with anoxidizing gas, such as oxygen, and a fuel gas, such as acetylene, by

hoses l0 and ll, respectively, which lead from a pair of quick-actingvalves V. Valves V are used' in turning on the oxygenand acetylene atthe beginning of each forward or hardening movement of carriage C, andin shutting off the heating gases as soon as each tooth has beentreated.

Blowpipes B and B may be any conventional type, each provided with asuitable mixer for forming a combustible mixture of oxygenand acetylenewhich passes to heads H and H through tubes IT, by which heads H and H'are supported. The normal amount of oxygen passing to the mixer ineither blowpipe is controlled by a regulating valve [3, while the normalflow oi acetylene to either mixer is controlled by a regulating alongthe path of travel of carriage C. For this purpose, a pinion I1 issecured to stem 18 of control valve l5 by a wing nut [9, while a similarpinion 20 is secured to stem '2! of control valve It by a wlngnut 22. Sothat valves I 5 and I 6 may be partially closed simultaneously and inequal amounts, and so that zpinions l1. and will always rotate in thesame direction,

an idler pinion, 23 is interposed between pinions l1 and 20. Idlerpinion 23 is rotatably mounted on the upper end of a post 24, in turnmounted upon a plate 25, the opposite ends of which are secured to thebodies of control valves 16 and thereby partially close control valvesl6 and I 6,

a rack 26 is secured in a horizontal position to the upper end of abracket 21, the lower end of which is secured to a flange 28 of track K.Rack 26 may be secured to bracket 21 and bracket 2'! to flange 28 in anysuitable manner, such as by bolts, as shown.

As soon as pinion ll engages stationary rack 26, the amount or pressureof oxygen supplied to blowpipes B and]? will begin to be reduced, andwhen the end of the tooth T is reached the amount of oxygen will befurther reduced. Thus.

'the longitudinal position of rack 26 and bracket 21 is preferably suchthat control valves [5 and- I6 will be partially closed when heads H andH reach the end of tooth T. For instance, rack 26 may be so positionedthat pinion 11 will engage the rack when the heating flames are at adistance of about in. from the end 'of tooth '1'. well as the relativesize of pinions ll, 20, 23 and rack 26 have been slightly exaggeratedfor the cake of clarity.) I

As soon as the heating flames reach the end of tooth T, both the oxygenand acetylene are turned off by valves V.-' The quenching fluid,normally water supplied to heads H and H 'by tubes 29, may be left onduring both the hardening and return strokes of carriage C; or thequenching water may be turned off as soon as the quenching jets pass theend of the tooth.

. 4 fuel gas, the heating flames will then be highly oxidizing and willtend to attack a surface heated to an elevated hardening temperature.Each of the above disadvantages isobviated by reducing the amount orpressure of'oxygen and providing thereby a carburizing or excessacetylene flame. Furthermore, although the resulting flames will becarburizing in effect, the amount of time during which the flames areapplied to the surface is relativelyshort. Thus, no appreciablecarburizing effect will be produced, since the reaction of a carburizingflame on highly heated surfaces is much slower than that of a highlyoxidizing flame.

Heads H and'H' may be of any suitable type, i

but it is preferred to use heads of the type disclosed in Roger 0. Dayapplication SerialNo. 169,333, flled October 16, 1937, now Patent No.2,224,006. Such heads are particularly adapted for hardening the wearingsurfaces of gear teeth, and are provided with a lower end 30 of reducedthickness adapted to fit in the valley between gear teeth. Such headsare also provided with two rows of combustible mixture outlets and tworows of quenching fluid outlets'which extend sub- 1 stantially from thebottom to the top of the gear tooth. The combustible mixture outlets areI spaced more closely together at the lower end of (In the drawing, thisdistance, as

each row, and at increasing distances apart toward the upper end of eachrow,'so that a greater amount of heat is applied adjacent the base ofthe gear tooth and an increasingly lesser amount toward the top of thetooth. This compensates for. the tendency for a greater amount of heatto be conducted from the base of the tooth into the body of the gear,and also prevents the top of the tooth from becoming over- Whileapparatus other than that describedabove may be used to reduce theamount or pressure of oxygen supplied to blowpipes B and B', a

particular advantage of the arrangement shown necessary to begintreatment of the next tooth.

There are many advantages in lowering the temperature and intensity ofheating fiames'by reducing the supply of oxygen, particularly in flamehardening operations. For instance, should it be attempted to lower theintensity and temperature of the heating flames by reducing the supplyof both oxygen and fuel gas, the velocity of the combustible mixturejets producing the heating flames will tend to be reduced to a pointbelow the rate of flame propagation, and backfires and/or flashbackswill result. A backfire, which is a popping back of the flame into theblowpipe, momentarily stops the operation; while a flashback, which is asustained burning of the mixture within the blowpipe, completely stopsthe operation. Again, should it be attempted to reduce the heatingefiect of the flames by reducing the amou t-oi heated.

The carriage C may beany conventional type of. mechanism, such as theself-propelled wheel carriage shown in U. S. Patent No. 2,183,605. Thetrack K may be an I-beam, as shown, or any other suitable track, such asa channel, along which the carriage may move.

The carriage C, as shown, is. provided with a horizontally adjustableslide 3|, which may be moved to any desired position by a hand wheel 32,and is also provided with a vertical slide 33 adjustable by meansof ahand wheel 34. The blowpipe support S is attached to vertical slide 33by a bolt 35, while valves V are mounted upon a suitable bracket 36,secured to horizontal slide 3|. Inlets 31 and 38 of valves V areconnected with suitable sources of oxygen and acetylene, respectively,or other oxidizing gas and fuel gas. Handles 38 of valves V also may beconnected by a common lever, if desired,'for simultaneous operation.

'Blowpipe'supiwrt S may be any suitable type adapted to permit thepositioning of blowpipes B and B so that heads H and H are disposed inthe desired relation with respect to the wearing surfaces of tooth T.Blowpipe support S may be similar to the support disclosed in theaforementioned application Serial No. 169,373, now Patent No. 2,224,006,but other supports may be used, such as disclosed in the application ofRoger filed October16, i937, now'Patent No. 2,224,007.

As illustrated herein, blowpipe support S comprises a horizontal arm I,one end of which is secured to slide 33 by bolt 35. A slotted verticalarm 42 is movable along arm 4| and may be secured thereto in any desiredposition by a bolt (not shown) which extends through the slot in i arm41. A slide 63, to which blowpipe B is se-- cured by a clamp 44, issimilarly adjustable along horizontal arm M. A second slide $5, to whichblowpipe B is secured by a clamp 96, is movable vertically along arm t2,and may ,be' secured in any desired vertical position by a bolt d1,which extends through the slot in arm d2. Through slides 93 and t5, andclamps M and t6, blowpipe 'B may be adjusted horizontally and radially,while ,blowpipe B may be adjusted vertically and radially. Thus, heads HandH' can be placed in any desired relationship with respect to thewearing surfaces of a gear tooth to be hardened,

while the support S, with the blowpipes B and B 0 While the apparatusdescribed is particularlyadapted .to harden the wearing surfaces of gearteeth, it will be understood that one, or more than two, blowpipes maybe used, and that such blowpipes may be provided with suitable heads fortreating other types of surfaces; Also, rack 26 may be placed in anydesired position to engage pinion l? and lower the intensity of theheating flame or flames at any desired point along the path of traverse.Furthermore, should it be desired to lower the intensity of the flame,and then raise the intensity of the flame as soon as a sur-- faceportion tending to become overheated is passed, suitable changes may bemade. For instance, in treating a flat surface of a plate or bar whichhas a slot or cutaway portion on the opposite side from the surfacebeing treated, a suitable rack may be placed to engage pinion 20 andthereby open valves 85 and it, after they have been partially closed byrack 26. With such .a setup, the intensity of the heating flame or.flames is lowered "as the surface portiondirectlyopposite the slot orcutaway portion is being treated, while the intensity of the heatingflame or flames is raised as soon as the surface portion opposite theslot is passed. Thus, previous and subsequent portions of the surfaceare heated to the same extent, while the portion opposite the'slot isheated to a lesser extent.

It will also be understood that this invention may be utilized inheating operations other than flame hardening and in treating. articlesother than gear teeth; andthat various changes in the apparatus, otherthan those indicated, may be made which will not depart from the spiritand scope of this invention, as defined in the appended claims.

What is claimed is: I i

produce a desiredcombustible mixturei. a third control means forpartially closing said third valve; and means for actuating said thirdvalve control means at a'predetermined point in the path of travel of'said carriage.

2. Apparatus forflame hardening a surface of a metal article as definedin claim 1, in which said third valve control means comprises, a pinionand said actuating means includes a rack-mount ed in a stationaryposition and operative to engage said pinion at a predetermined point inthe path of travel of said carriage.

3. Apparatus as defined in claim 1, in which said carriage is movableforward and rearward along a path adjacent said article and saidactuating means is constructed and arranged to partially close saidthird valve at apredeter-- mined point in the path of forward travel ofsaid carriage and to reopen said third valve during subsequent rearwardtravel of said carriage.

4. Flame hardening apparatus comprising a heating torch having a tip anda mixer in which oxygen and fuel gas are brought together and suppliedto the tip; two adjustable valves for severally initially adjusting theflow of fuel gas and the flow of oxygen to said mixer, to initiallyproduce a desired combustible mixture; a. conduit through whichoxidizing gas is suppliedto the torch; a third valve controlling theoxidizing gas flow through said conduit; and means for operating thethird valve progressively in response to displacement of the. torch tovary the intensity of the flame, to change only the supply of oxidizinggas during a flame hardening operation.

5. In an apparatus for heating a metal. surface, a blowpipe constructedand arranged to produce a mixture of fuel and oxidizing gases to providea heating flame, two adjustable valves for severally initially adjustingthe flow of fuel gas and the flow of oxygen to said heating flame,

means for efiecting relative movement between the blowpipe and the metalsurface, means including a third valve for reducing the flow of the 1.Apparatus for flame hardening a surfaceoxidizing gas only and withoutvarying the flow of the fuelgas toreduce the intensity of the heatingflame, and means for operating said third valve at a predetermined pointin the movement between the blowpipe and the work surface.

AM B. GILSON.

REFERENCES CITED 'The following references are of record in the flleofthis patent UNITED STATES PATENTS Number V Name Date 1,711,633 DornseifMay 7, 1929 2,065,627 Taylor Dec. 27, 1936 2,067,549 Sykes Jan. 12, 19372,076,515 Kinzel Apr. 6, 1937 2,089,015 Bucknam Aug. 3, 1937 2,089,029Jones Aug. 3, 1937 2,102,040 Slade 1. Dec. 14, 1937 2,124,459 BurgessJuly 19, 1938 2,189,460 Derhammer 1 Feb. 6, 1940 2,196,902 Jones Apr. 9,1940 2,202,758 Denneen May 28, 1940 2,220,002 Rollman Oct. 29, 1940FOREIGN PATENTS Number Country Date 446,821 Great Britain May 4, 1936494,218 Great Britain Oct. 21, 1938 Certificate of Correction Patent No.2,440,716. 1 I May 4, 1948.

HIRAM B. GILSON It is hereby certified that errors appear in the printedspecification of the above numbered patent requirin correction asfollows: Column 2, line 42, for tubes 17 read tubes 12; column 3, e 39,for the word cake read sake; column 6, line 1, a

after a third insert valve for controlling the flow of oxygen throughone of said adjust able valves to said mixer; and that the said LettersPatent should be read with these j corrections therein that the samemay. conform to the record of the case in the Patent Ofice.

Signed and sealed this 6th day of July, A. D. 1948.

r THOMAS F. MURPHY,

Assistant Commissioner of-Patente.

